Development of Ilmenite-type Electronic Material CdTiO 3 for Devices Truptimayee Acharya and R N P Choudhary Department of Physics, Institute of Technical Education and Research Siksha ‘O’ Anusandhan University, Khandagiri, Bhubaneswar-751030 (Odisha) India ABSTRACT The correlation between structural and electrical properties of cadmium titanate (CdTiO 3 ) ceramic was established through X-ray diffraction combined with electrical and optical characterization techniques. The compound was prepared using a high- temperature solid-state reaction technique. Preliminary study on some structural aspect of the material using X-ray diffraction pattern showed the formation of single- phase compound in orthorhombic crystal system. Some characteristics of molecular structure of the material were studied by using Fourier transform infrared spectroscopy and ultraviolet visible spectroscopy techniques. The size and distribution of grains in the scanning electron micrograph revealed the polycrystalline nature of the material with size anisotropy and small number of voids. Detailed analysis of temperature-frequency dependence of dielectric parameters (i.e. dielectric constant and tangent loss) has revealed many interesting and important results of the material. The impedance studies of CdTiO 3 over a wide range of temperature and frequency in the complex plane formalism with suitable equivalent circuit have shown some correlation between microstructure and electrical properties of the material. From the impedance and dielectric measurements some electrical parameters such as bulk resistance, capacitance, relaxation time and relative dielectric constant were calculated. The variation of DC conductivity with inverse of absolute temperature follows the Arrhenius relation. The study of frequency dependence of AC conductivity suggests that the material obeys Jonscher’s universal power law. Index Terms ─ X-ray diffraction pattern, Fourier transform Infrared spectroscopy, Dielectric measurements, Conductivity. 1 INTRODUCTION IN recent years the titanium based metal oxides are of great interest due to their high refractive index, wide energy band- gap and low absorption properties [1]. Amongst these oxides some of the transition metal titanates of a general formula MTiO 3 : M= Fe, Co, Cd, Mn, Ni, Mg etc. (also known as the ilmenites) are considered very important chemical and electrical materials, because of their wide applications in industries such as semiconductor rectifiers, electrodes of solid oxide fuel cell, metal–air barriers, hydro-carbonate catalyzers, color mixtures of surface coating and gas sensing devices, etc. [2, 3]. These metal titanates crystallize either into ilmenite structure or perovskite structure. As reported earlier, CdTiO 3 crystallizes into ilmenite phase below 1000 0 C and into perovskite phase above 1000 0 C [4, 5]. CdTiO 3 is unique in its structure and nature. All the metal titanates exhibiting ferroelectric phase transitions possess the paraelectric cubic phases and the ferroelectric tetragonal phases, whereas in CdTiO 3, both the paraelectric and ferroelectric phases have orthorhombic structures with different crystal symmetry [6]. It was demonstrated in the previous reports of Yang et al [7], Shan et al [8] and few others that CdTiO 3 undergoes a displacive ferroelectric phase transition at about 80 K. At this temperature CdTiO 3 undergoes a phase transition from the centrosymmetric orthorhombic to a non-centrosymmetric orthorhombic structure. The break in symmetry of the positions of Ti and O ions along the long axis and their shift relative to the Cd cation introduces a dipole moment, so the low-temperature phase of the material is ferroelectric while still retaining overall orthorhombic symmetry [6]. As a result of its structural phase transition, it has the potential applications in nonlinear optics [7], and it can also serve as a wide band gap (E g =3.7 eV) semiconductor. CdTiO 3 has also been used as a conductive material [9], optical fibers [10], humidity sensor [11], and photo catalytic [12]. Though ample researches have been reported on the phase transition of CdTiO 3 , there are still some contradictions on its precise structure and properties. Yang et al. [6] had reported that CdTiO 3 crystallizes into the ilmenite or perovskite phase, Manuscript received on 28 January 2015, in final form 9 April 2015, accepted 18 May 2015. IEEE Transactions on Dielectrics and Electrical Insulation Vol. 22, No. 6; December 2015 3521 DOI: 10.1109/TDEI.2015.005196